[NET-730] Cannot connect to FTP server with HTTP proxy

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.10.0
• Fix Version/s: 3.11.0
• Component/s: FTP
• Assignee: Gary D. Gregory
• Reporter: Johannes Thalmair
• Created: 23/May/24 11:54
• Updated: 27/May/24 07:54
• Resolved: 26/May/24 19:04

Description

After updating from Commons Net 3.9.0 to 3.10.0, I can no longer connect to an FTP server with an HTTP proxy that requires authorization. Sadly I do not have direct access to that server and don't know which proxy is running there. A try to connect just blocks for 5 minutes and then fails with an IOException: No response from proxy

    at org.apache.commons.net.ftp.FTPHTTPClient .tunnelHandshake(FTPHTTPClient .java:209)

    at org.apache.commons.net.ftp.FTPHTTPClient .connect(FTPHTTPClient .java:173)

 

I'm using the org.apache.commons.net.ftp.FTPHTTPClient for connecting and already did some debugging. The change that causes my problem is the switch from the deprecated org.apache.commons.net.util.Base64.encodeToString(byte[]) to java.util.Base64.getEncoder().encodeToString(byte[]) to encode the Proxy-Authorization header in FTPHTTPClient.tunnelHandshake() (see https://github.com/apache/commons-net/commit/396bade29ad98d20a2c039ac561db56b63018b39) The old encoding method added a CRLF / "\r\n" to the end of the String, while the new one does not. This specific proxy seems to expect it, I don't know if others do, too.